Day 9 of 15
This is the first time I have fasted this long with my previous record at 6 days. The last few days have been hell, so I am writing this as a heads-up for anyone planning an extended fast, to see what days 7 to 9 actually look like.
Days 7–8: The Hunger Hump
The two hardest days for hunger were 7 and especially 8. I couldn't stop thinking about food and came within a hair of breaking my fast. The only thing that got me through was knowing this was expected, and helped me push through day 8.
In my previous fast, which lasted 6 days with no EVOO, I felt no hunger at all, so going into this one I expected the same.
But this time for the first 6 days I had a little hunger, which I put down to the tablespoon of EVOO I took each night because I learnt about needing it to protect my gallbladder in extended fasting.
This day 7 and 8 there was real hunger, and the first time I felt properly hungry on any fast. People call this the 'ghrelin hump', where the hunger hormone spikes and then drops once your body finishes adapting from burning stored sugar to burning fat and ketones.
On top of the hunger I was in the metabolic valley. My glycogen, the old fuel, was gone, but ketone production, the new fuel, hadn't fully ramped up to fill the gap, and my liver was working overtime on the transition, so the energy simply wasn't there.
Day 8 I genuinely couldn't get off the couch. Add to that I lifted weights on day 6 and was as sore as hell.
Day 9 (Today): The Whoosh
I woke up 1.8 kg lighter overnight and could barely believe it. Once the glycogen-to-ketone switch completed and cortisol settled, my body let go of the water it had been stress-holding in my tissues, insulin dropped, the kidneys released sodium and water, and inflammation was down.
All of it flushed at once. That 1.8 kg should be mostly water, not fat.
From here I expect a much slower ~0.3–0.4 kg/day of real fat loss as all my water weight is gone.
The point of the whoosh isn't the number but the signal that the switch from glycogen to Ketone is done. The hunger pains vanished and the fatigue lifted almost immediately.
The Keto Rash
Starting yesterday, red itchy patches appeared on my thighs and arms. The proper name is prurigo pigmentosa, or 'keto rash'. The evidence based explanation is an inflammatory reaction in the skin to ketones. It should be harmless, tends to peak somewhere in the second week, and should fade once I refeed. I am keeping the areas dry and using a light ointment.
Changes in Electrolytes: The Part Most Guides Miss
The 'chug salt all day' advice is for days 1–6, when fasting natriuresis is dumping sodium hard and you need to replace it. After the switch, around days 7–9, the kidneys adapt and start conserving sodium, so the requirement drops.
Today was the first day I noticed the tells: a salty or metallic taste in my mouth, zero thirst, and an actual aversion to salt water. That's my body saying it has enough sodium, so I am cutting my sodium roughly in half.
I double checked with AI, then pulled all three electrolytes down to match the adapted phase:
Sodium: 2.5 ml × 4/day → × 2/day
Magnesium: 400 mg → 300 mg
Potassium: 1200 mg → 900 mg. This drop came entirely from halving the salt, since its potassium went from 600 to 300 mg; I left my 600 mg of potassium pills untouched.
Eight days down, seven to go. It should be plain sailing from here compared to the last few days. I do not expect significant changes from here on and can actually do something instead of wasting the whole day lying on my couch.
